Creep tests were performed over a range of stresses and temperatures on a 3Y-TZP/20% Al2O3 composite termed 3Y20A. After creep, measurements were undertaken to determine the average shapes and sizes of the zirconia and alumina grains. The experimental data are compared with creep models including interface-controlled diffusion creep. The results suggest that interface-controlled diffusion creep is important at the lower stress levels but grain boundary sliding may be accommodated by intragranular slip within the alumina grains at the higher stresses.